Role of tantalum in the hot corrosion of a Ni-base single crystal superalloy

Chang, Jianxiu; Wang, D.; Liu, Ting; Zhang, Guoren; Lou, Langhong; Zhang, J.

doi:10.1016/j.corsci.2015.05.066

Cited by 52 publications

(17 citation statements)

References 38 publications

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“…The results show that all corrosion processes of the untreated Ta and LSM‐treated specimens in chloride melts produced NaTaO 3 and Na 2 Ta 4 O 11 . Similar results have also been reported for the corrosion testing of Ta‐containing alloys in melt salts and after experiments to fabricate NaTaO 3 and Na 2 Ta 4 O 11 using sodium salt fluxes …”

Section: Resultssupporting

confidence: 85%

The effect of surface treatment on the corrosion behavior of a pure Ta sheet in an equimolar NaCl–KCl melt at 850°C in air. Part 1: Laser surface melting

Zeng

et al. 2019

Materials & Corrosion

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The corrosion behavior of pure Ta and laser surface melting-treated Ta sheets was investigated in an equimolar NaCl-KCl melt at 850°C in air. The results show that the predominant factors involved in the consumption of materials were reactions that form sodium-containing oxides and Ta 2 O 5 . High corrosion stress led to slip of the untreated Ta surface grains, further resulting in preferential corrosion along slip bands. The slip of surface grains substantially deteriorated the bonding between the corrosion scale and matrix, thus leading to rapid degradation of the corrosion scale. The melt layer consisted of a thin Ta 2 O 5 film, and the inner dendrite layer demonstrated self-healing characteristics during corrosion and presented a better hot corrosion resistance than the untreated Ta owing to the excellent bonding at the scale and melt layer interface. K E Y W O R D S chloride, hot corrosion, LSM, oxidation, Ta

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Section: Resultssupporting

confidence: 85%

The effect of surface treatment on the corrosion behavior of a pure Ta sheet in an equimolar NaCl–KCl melt at 850°C in air. Part 1: Laser surface melting

Zeng

et al. 2019

Materials & Corrosion

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“…Other studies reported the formation of stable Cr-Ti sulfides in the denuded zone beneath a surface oxide scale. [24,25] A finding subsequently confirmed by Chang et al, [26] who corroded their alloy for 80 hours in a sulfur and oxygen containing environment, and which is consistent with our current work, shown in Figures 5 and 11. The formation of chromium sulfides is considered undesirable, as the sulfidation rate of chromium is four to five orders of magnitude faster than the corresponding oxidation rate, preventing the formation of a protective scale.…”

Section: A Comparing Surface and Crack Tip Behaviorsupporting

confidence: 92%

“…[28] Several previous studies on the additions of refractory metals, including Mo, W, Ta, and Nb, to improve corrosion resistance were performed. [30,31] Critically, the sulfidation rates measured for these metals were similar to the rate of oxidation of chromium in nickel superalloys. [30] Ellingham diagrams showing the free energy and partial pressures required for the formation of metallic sulfides show that the most stable is tantalum sulfide TaS 2 , closely followed by Hf 3 S 2 .…”

Section: Effect Of Refractory Elementsmentioning

confidence: 62%

On the Effect of Environmental Exposure on Dwell Fatigue Performance of a Fine-Grained Nickel-Based Superalloy

Pedrazzini

Child

Aarholt

et al. 2018

Metall Mater Trans A

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The influence of sulfur contamination on the corrosion-fatigue behavior of a polycrystalline superalloy used in aero-engines is considered. Samples tested under a variety of environmental conditions (including exposures to air, SO x gas, and salt) are characterized through a suite of high-resolution characterization methods, including transmission electron microscopy (TEM), secondary ion mass spectroscopy (nanoSIMS), and atom probe tomography (APT). The primary effect of sulfur contamination is to accelerate the crack growth rate by altering the failure mechanism. The SIMS and TEM analyses indicate Cr-Ti sulfide particle formation at grain boundaries ahead of and around oxidized cracks. The APT analysis suggests that these particles then oxidize as the crack propagates and are enveloped in chromia. The chromia is surrounded by a continuous layer of alumina within the cracks. All of the sulfur detected was confined within the particles, with no elemental segregation found at grain boundaries.

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“…Thus, the hot corrosion mechanism for CM247LC alloy transitions from basic fluxing during the initial stages (30 to 60 minutes) to alloy-induced acidic fluxing in the later stages of exposure. Such a changeover of fluxing mechanism from basic to acidic has also been reported for Mo containing B1900 superalloy by Fryburg et al [38] and Giggins et al [43] Ta present in the alloy is expected [44,45] to show beneficial effect on hot corrosion resistance of the alloy against molten salt. The oxide of Ta i.e., Ta 2 O 5 binds with Na 2 O and forms solid NaTaO 3 .…”

Section: Discussionsupporting

confidence: 67%

“…The oxide of Ta i.e., Ta 2 O 5 binds with Na 2 O and forms solid NaTaO 3 . Preferential formation [44,45] of solid NaTaO 3 prevents the formation of molten Na 2 WO 4 and Na 2 MoO 4 , which provides some resistance against alloy-induced acidic fluxing. However, the degradation mechanism is primarily governed by detrimental effects of W because the alloy has higher W content than Ta.…”

Section: Discussionmentioning

confidence: 99%

Type-I Hot Corrosion of Ni-Base Superalloy CM247LC in Presence of Molten Na2SO4 Film

Kumawat

Parlikar

Alam

et al. 2020

Metall Mater Trans A

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Type-I hot corrosion behavior of CM247LC superalloy is evaluated in the air at 950°C against low (3 to 4), intermediate (7 to 9), and high (12 to 14 mg cm À2) Na 2 SO 4 deposits. Duration of thermal exposure is varied from a very short duration of 5 minutes to long duration of 1000 hours. The alloy shows poor corrosion resistance and undergoes complete disintegration after 500 hours of thermal exposure. Degradation of alloy increases with the increase in the duration of exposure as well as the initially deposited amount of the salt. Based on the systematic analysis of the corrosion scale, degradation mechanisms supported by the microstructural evidence are proposed. Fluxing, sulfidation-oxidation, and sulfide-undercutting are reported as the primary degradation mechanisms for CM247LC alloy in the presence of Na 2 SO 4. Self-sustaining degradation of alloy leading to complete disintegration of specimen is caused by the changeover of fluxing mechanism from basic fluxing to alloy-induced fluxing.

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Role of tantalum in the hot corrosion of a Ni-base single crystal superalloy

Cited by 52 publications

References 38 publications

The effect of surface treatment on the corrosion behavior of a pure Ta sheet in an equimolar NaCl–KCl melt at 850°C in air. Part 1: Laser surface melting

The effect of surface treatment on the corrosion behavior of a pure Ta sheet in an equimolar NaCl–KCl melt at 850°C in air. Part 1: Laser surface melting

On the Effect of Environmental Exposure on Dwell Fatigue Performance of a Fine-Grained Nickel-Based Superalloy

Type-I Hot Corrosion of Ni-Base Superalloy CM247LC in Presence of Molten Na2SO4 Film

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